Conventionally, there are known gas sensors to be mounted on an exhaust pipe of an internal combustion engine or the like of a vehicle for detecting a concentration of a specific gas contained in an exhaust gas as a measurement gas. The gas sensors include ones which include a sensor element that detects a specific gas concentration contained in a measurement gas, a housing holding the sensor element inserted thereinto, and an element cover disposed on the distal end side of the housing.
For example, patent document 1 discloses a gas sensor provided with a double-structured element cover for preventing a sensor element from being flooded and so on, the double-structured element cover including an inner cover for covering a distal end portion of the sensor element provided with a gas inlet part, and an outer cover disposed outside the inner cover. The outer cover of this gas sensor is provided with outer inlet openings for introducing a measurement gas into the outer cover.